1. Field of the Invention
This invention relates to a precision generator and distributor device for plasma in electro-thermal chemical gun systems. In particular, a self-adjusting filament provides a controlled amount of high temperature and high pressure plasma in a capillary in cooperation with perforations in the capillary wall and nozzles in partition walls to enable temporal and spatial distribution of the plasma into a combustible chemical mass to thereby control combustion and achieve high ballistic and piezometric efficiencies.
2. Description of the Prior Art
U.S. Pat. No. 4,711,154 Chrysomallis et al discloses a pressure amplification system in which plasma is created by exploding or evaporating a fuse wire in a capillary. Unlike the present invention, this prior art starts the plasma instantaneously and as a result high ohmic resistance develops in the capillary. Such high ohmic resistance, encountered in the early stages of plasma development, is undesirable because it limits the geometric dimensions and energy content, i.e. the length, width, thickness and energy per unit length of the plasma arc for a given power supply. Further, fuse wires produce considerable shock waves which are propagated by a burning propellant or chemical mass and results in undesirable pressure spikes in the combustion chamber.
Similarly, U.S. Pat. No. 4,895,062 Chrysomallis et al discloses an impulse propulsion gun system wherein high pressure and temperature are created in a gun breech block with initial ignition provided by a plasma source. The plasma is generated in a capillary using a fuse wire which evaporates under the influence of a high voltage and current input. The plasma arc and discharge in this prior art are developed instantaneously and depend upon the consumption of the fuse wire by the high voltage and current from a power supply. High ohmic resistance is encountered in the early stages of the plasma arc development in the capillary because a small increase in current across the fuse wire requires a substantial increase in voltage.
Furthermore, in the judgement of the applicant, in most prior art concerning electrothermal-chemical gun systems wherein high pressure and temperature plasma is used for ignition and combustion enhancement an exploding or consumable fuse is employed to create a plasma within a container. Heretofore, such fuse wires have encountered several operational problems in regard to high ohmic resistance, geometric consistency of plasma, controllability and repeatability of plasma, and chamber pressure control under given power supply conditions.
The present invention overcomes all of the limitations of the prior art which are attributable to the fuse wire and provides several advances over the prior art. Some of the most important distinguishing features include the use of a filament which has variable cross-sectional area and mass per unit length. Particularly, the filament is constructed to have an infinite adjustment to thereby enable variations in geometric dimensions and mass such that a predetermined ohmic resistance is set to start a plasma arc slowly under the influence of a known power supply. More particularly, by adjusting the filament, a near exact length of plasma arc can be created in a capillary. As will be seen in the ensuing discussions herein below, such a precise control over the dimension of the plasma arc enables control over the energy content, consistency and repeatability of the plasma discharge, and chamber pressure which ultimately results in a precise control over a plasma arc initiated ignition and combustion of a propellant mass to thereby optimize piezometric and ballistic efficiencies.